A painting apparatus is disclosed in Japanese Patent Application Laid-Open Publication No. 11-267560 (JP 11-267560 A). In this painting apparatus, a painting gun is provided to a painting robot, wherein a color changing valve unit for switching paints and a paint cartridge filled with a paint are provided to an arm section of the painting gun. A paint whose usage frequency is high is supplied to the painting gun via the color changing valve unit, and a paint whose usage frequency is low is supplied to the painting gun from the paint cartridge.
The painting apparatus disclosed in JP 11-267560 A will be described below with reference to FIG. 9 hereof.
A painting apparatus 200 shown in FIG. 9 comprises a manipulator 201 of a painting robot; a painting gun 202 mounted on a distal end of the manipulator 201; a color changing valve unit 204 and a paint cartridge 206 mounted on the manipulator 201; and a paint feed device 208 connected to the color changing valve unit 204 via a plurality of paint feed tubes 207. Reference numeral 209 shows a first arm of the manipulator 201, and reference numeral 210 shows a second arm of the manipulator 201. The color changing valve unit 204 and the paint cartridge 206 are mounted on the second arm 210.
If, for example, the color changing valve unit 204 or the paint cartridge 206 are positioned a large distance away from the painting gun 202, then when air inside a paint feed channel between the color changing valve unit 204 (or the paint cartridge 206) and the painting gun 202 is expelled by filling the paint feed channel with paint from the color changing valve unit 204 or the paint cartridge 206, the speed at which the paint feed channel is filled will vary dramatically depending on the viscosity of the paint and the ambient temperature. As a result, when the filling speed increases, the amount of discarded paint increases, and the amount of paint required for painting may occasionally be insufficient.
Additionally, since the color changing valve unit 204 and the paint cartridge 206 are attached to the manipulator 201, the moment of inertia of the to manipulator 201 increases, and movements such as quick swiveling become difficult. Moreover, the power for operating the manipulator 201 also increases. Furthermore, the size of the moving part increases, which may make painting tasks harder to perform in a cramped place.